Recently, reduction in size of an optical transceiver (transponder) and reduction in cost thereof have progressed.
According to this, even in an optical modulator module that is mounted in an optical transceiver, a reduction in footprint size is in progress, and a method, in which usage of a coaxial connector is avoided and a plurality of signal lines are collectively surface-mounted for connection, is employed in industry specifications (OIF2014.099.00). Research and development of the method are in progress.
In this regard, there is known an optical modulator module including an optical modulator including a signal electrode and a ground electrode, a conductive housing that accommodates the optical modulator and is electrically connected to the ground electrode of the optical modulator, a substrate in which aground electrode that is connected to an external wall of the housing with solder or a conductive adhesive is formed on one surface, and a signal electrode is formed on the other surface, and a lead pin that electrically connects the signal electrode of the optical modulator and the signal electrode of the substrate (refer to Patent Literature No. 1).
In addition, there is known an optical modulator including a substrate having an electro-optic effect, an optical waveguide that is formed on the substrate, an optical modulation element including a modulation electrode configured to modulate light that passes through the inside of the optical waveguide, and a connection substrate that is disposed on an outer side of the substrate and supplies a microwave signal for driving the optical modulator element to the optical modulator element. A signal input end and a signal output end are formed on the connection substrate, and the connection substrate is provided with reimaging suppression means that suppresses recoupling of a radiation mode of the microwave signal, which is input to the signal input end, to the signal output end (refer to Patent Literature No. 2).